1. Field of the Invention
This invention relates generally to remotely controlled systems employing a transmitter and a receiver and more particularly to a self-contained monitor for surveilling a predetermined space wherein the monitor is responsive to an authorized remote controller transmitting a particular radio-frequency (RF) carrier signal under the control of a user.
2. Description of Related Art
Intrusion detection systems employing remotely controlled self-contained monitors surveilling predetermined spaces are known in the prior art. Such monitors present certain problems because they are often disposed in areas where an intruder may have the time and the privacy to examine the monitor and, unbeknownst to the user, reset the monitor to cause the user to enter the predetermined space unaware that the intruder is in the area waiting to surprise the user.
U.S. Pat. No. 3,906,348, which issued to Colin B. Willmott on Sep. 16, 1975 discloses a digital radio control system comprising a transmitter and receiver wherein a plurality of two position switches may be set in a transmitter to pick a particular code which will be transmitted, and in which a plurality of switches in a receiver may be set to a particular code such that if the same code is selected in the receiver as is set in the transmitter, the receiver will be energized upon receipt of the code. In a typical application of Willmott's radio control system such as a remotely controlled garage door opener, the switches in the receiver are generally accessible to a user who relies on observing the switch settings in order to duplicate them on either a replacement remote controller, if the original is lost or broken, or on additional remote controllers should the user authorize other individuals access to his or her garage. Willmott does not address the problem of a receiver in an intrusion monitor which is controlled by a remote controller and which is used to surveil a predetermined space wherein an intruder can observe the code setting in the monitor and use it to program an unauthorized remote transmitter in order to control the monitor.
U.S. Pat. No. 4,383,242, which issued to Nathan Sassover and William A. Rennie on May 10, 1983 teaches a remotely controlled anti-theft system employed on an automobile which is armed only when a hand held coded transmitter is operated and is disarmed upon a subsequent operation of the transmitter. Sassover ensures the secrecy of the signaling code used to operate the system through the use of a resistor code cartridge installed in the transmitter and a resistor code cartridge installed in a receiver. As disclosed by Sassover, the resistors in his code cartridges are laser-trimmed to 1% accuracy in a factory in order to tune the transmitter to the receiver. Sassover does not teach a simple and inexpensive means by which a user can install and secrete the signaling code in the receiver in order to tune it to the particular carrier signal transmitted by the coded transmitter.
U.S. Pat. No. 4,897,630, a continuation-in-part of U.S. Pat. No. 4,794,368, which issued to Michael Nykerk on Jan. 30, 1990 discloses a computerized alarm system for detecting, signaling and reporting the occurrence of a penetration toward or an unauthorized entry into a defined area, such as an automobile. It also discloses a self-contained monitor intended to protect a variety of objects such as a boat, a trailer, a house, etc. and which communicates with a remote controller in a similar manner as taught in U.S. Pat. No. 4,794,368. Nykerk discloses a multi-button remote controller associated with a multichannel system wherein a user pressing any button once or pressing any combination of the buttons simultaneously controls a number of separate functions. In one embodiment of his disclosure, he teaches that the remote controller may be used as a garage door opener as well as the transmitter for the alarm system. Nykerk's self-contained monitor employs a programming device which plugs into a control module in his monitor. An installer, through the use of a keyboard that forms part of the programming device, inputs certain operating options into the monitor. However, Nykerk does not disclose a self-contained monitor which includes an inexpensive and simple means for a user to set and secrete a code in the monitor to tune it to a carrier signal transmitted by the remote controller.
U.S. Pat. No. 5,808,547, a continuation-in-part of U.S. Pat. No. 5,621,385, which issued to the applicant of the present invention, William P. Carney, on Sep. 15, 1998 discloses an intrusion detection system used to surveil a predetermined space wherein a self-contained monitor may be armed, disarmed and tested by a remote controller transmitting an RF signal initiated by a user manipulating a button switch. The disclosure teaches that the transmitting device operates in a manner similar to a garage door opener but does not teach a self-contained monitor comprising a means, accessible to the user, for setting and secreting a code in the monitor for tuning the monitor to the RF carrier signal transmitted by the remote controller.
As can be seen from the prior art, existing alarm systems which include a self-contained monitor responsive to an authorized remote controller transmitting a particular RF carrier signal under the control of a user do not solve the problem of providing a simple and inexpensive means, accessible to the user, for setting and secreting a code in the monitor such that the code tunes the monitor to the particular RF carrier signal and such that the code setting cannot be determined by an intruder.